nandi/jolt-native · core.clj

⑂ c131fc627e173c8f2ca84d0f2809ac8b22dc1a03

core.clj · 400 lines · 16.2 KBClojure    Blame HistoryRaw
Write dvui's shape in jolt, on SDL3, with no shared object  Veronika Winters 1(ns glimmer-jvui.core
"A glimmer backend that renders through [jvui](../../../jvui).
 glimmer owns the reactive core — ratoms, components, the reconciler — and
 knows nothing about any toolkit. glimmer-gtk fills that in with GtkWidgets,
 glimmer-vidya with a Rust node arena painted by egui, glimmer-gfx with a
 software rasterizer it writes itself. This fills it in with jvui, and so is
 the smallest of the four: everything a backend usually has to supply — the
 measuring, the placing, the hit testing, the painting — is already a toolkit
 one directory over.
 What is left is the half an immediate-mode library does not have: a tree to
 hold still between frames. The reconciler needs somewhere to put a widget it
 created and to append a child to, and jvui's widgets draw and return within
 one call. So a node here is an atom of {:tag :props :children :key}, about
 thirty lines of it, and once a frame `emit!` walks that tree and calls the
 jvui widget each node names.
 # The walk is the closure
 glimmer-vidya's README explains why its tree lives in Rust: `ScrollArea` and
 `Frame` take an `FnOnce(&mut Ui)` and keep their begin/end private, so a
 push/pop ABI cannot scroll a page. jvui's containers take a body function
 for the same reason, and here the recursion *is* that function — `emit!` on
 a container passes `emit-children!` as the body, and the nesting takes care
 of itself.
 # Why every node carries a key
 jvui identifies a widget by its parent and its index among its siblings,
 unless it is given a `:key`, which replaces the index. A reconciler reorders
 children; an identity built on the index would hand each widget after the
 moved one the caret, the scroll offset and the drag of whichever widget used
 to sit at its index. So every node gets a serial number at creation and
 passes it as its key, and the identity follows the node rather than its
 position. That is the bug class zvui's README describes from the backend
 side, closed here at the other end."
(:require [glimmer.backend :as b]
          [jvui.app :as app]
          [jvui.core :as c]
          [jvui.theme :as theme]
Give jvui a picture from somewhere else, and a clock   42            [jvui.widgets :as w]
Answer the rest of what a client asks its window   43            [jvui.frames :as frames]
          [jvui.host :as host]))
Write dvui's shape in jolt, on SDL3, with no shared object  Veronika Winters 45
46;; --- the retained tree -------------------------------------------------------
48(defonce ^:private serial (atom 0))
50(defn- create! [tag props]
(atom {:tag tag :props props :children [] :key (swap! serial inc)}))
53(defn- apply-props! [_tag n props] (swap! n assoc :props props) nil)
54(defn- append-child! [_t parent child] (swap! parent update :children conj child) nil)
55(defn- remove-child! [_t parent child]
(swap! parent update :children #(vec (remove #{child} %))) nil)
57(defn- replace-child! [_t parent old new]
(swap! parent update :children #(mapv (fn [c] (if (= c old) new c)) %)) nil)
59(defn- reorder-child! [_t parent child sibling]
(swap! parent update :children
       (fn [cs]
         (let [cs (vec (remove #{child} cs))
               i (if (nil? sibling) 0 (inc (.indexOf cs sibling)))]
           (vec (concat (subvec cs 0 i) [child] (subvec cs i))))))
67;; --- props -------------------------------------------------------------------
69(defn- txt [props] (str (or (:label props) (:text props) "")))
71(defn- num [v default] (if (number? v) (double v) default))
73(defn- box-opts
"The container options shared by every container tag."
[props key]
(cond-> {:key key
         :dir (if (= :horizontal (:orientation props)) :horizontal :vertical)}
  (:spacing props) (assoc :spacing (num (:spacing props) 0.0))
  (:padding props) (assoc :padding (num (:padding props) 0.0))
  (:margin props)  (assoc :margin (num (:margin props) 0.0))
  (:expand props)  (assoc :expand (:expand props))))
83(defn- fire! [n k & args]
(when-let [f (get (:props @n) k)] (apply f args)))
86;; --- the walk ----------------------------------------------------------------
88(def ^:dynamic *record-rects?*
"When true, each node keeps the rectangle jvui gave it, under `:rect`.
 Off in a running window, where it would be a `swap!` per node per frame for
 nobody's benefit. On under `render-once`, so a test can click the centre of
 a button the way a person would, rather than guessing at a coordinate and
 re-guessing every time a padding changes."
97(declare emit!)
99(defn- record! [n id]
(when *record-rects?* (swap! n assoc :rect (c/rect-of id)))
103(defn- emit-children! [n]
(fn [_id _rect] (doseq [c (:children @n)] (emit! c))))
106(defn- emit!
"Render one node, and through it everything below it.
 A widget answers what the person did to it, and that answer is turned back
 into the callback prop the component registered — which is the whole seam
 between an immediate-mode toolkit and a retained, callback-shaped one."
(let [{:keys [tag props key]} @n
      s (txt props)]
  (case tag
    :page (w/page* (cond-> {:key key}
                     (:max-width props) (assoc :max-width (:max-width props)))
                   (emit-children! n))
    (:card :frame) (w/card* (box-opts props key) (emit-children! n))
    :scroll (w/scroll* (assoc (box-opts props key)
                              :height (num (:height props) 200.0))
                       (emit-children! n))
    :hbox (c/box* (assoc (box-opts props key) :dir :horizontal)
                  (emit-children! n))
    (:vbox :box) (c/box* (box-opts props key) (emit-children! n))
Take the eight tags a client still had nowhere to put   131      ;; ONE tag for both kinds of picture: `:feed` is live pixels pushed
    ;; in under a name and re-uploaded as they arrive, `:src` is a file
    ;; decoded once and kept by path. Everything downstream — the fit, the
    ;; bounds, the click — is the same, which is why libvidya makes this a
    ;; prop and not a second tag, and why frq writes [:image {:feed k}]
    ;; for a call tile and [:image {:src p}] for an attachment.
    ;; The pixels never go through the reconciler either way: a frame
    ;; arrives when the network says so, and a props diff at thirty a
    ;; second would be a re-render per frame per peer.
    :image (let [id (c/next-id key)
                 rect (w/image {:feed (:feed props) :src (:src props)}
                               {:fit (:fit props)
                                :max-width (:max-width props)
                                :max-height (:max-height props)
                                :size (:size props)
                                :expand (:expand props)})]
             (record! n id)
             (when (:clicked? (c/interact! id rect)) (fire! n :on-click)))
    :title-2 (w/title-2 s)
    :status (w/status s (boolean (:live props)))
    :spinner (w/spinner s)
    :link (let [id (c/next-id key)]
            (record! n id)
            (when (w/link s {:key key}) (fire! n :on-click)))
    :emoji (w/emoji (or (:emoji props) s) (:size props))
    :avatar (w/avatar (or (:label props) s)
                      (cond-> {}
                        (:src props)  (assoc :src (:src props))
                        (:size props) (assoc :size (:size props))))
    :reaction (let [id (c/next-id key)
                    glyph (or (:emoji props) s)]
                (record! n id)
                (when (w/reaction glyph {:count (or (:count props) 0)
                                         :mine? (boolean (:mine props))
                                         :size  (:size props)
                  (fire! n :on-click)))
Give jvui a picture from somewhere else, and a clock   176
Write dvui's shape in jolt, on SDL3, with no shared object  Veronika Winters 177      :title (w/title s)
    :label (if (:dim props) (w/dim-label s) (w/label s))
    :dim-label (w/dim-label s)
    :button (let [id (c/next-id key)
                  hit? (w/button s {:key key :kind (or (:kind props) :normal)})]
              (record! n id)
              (when hit? (fire! n :on-click)))
Take :checkbutton, which is :checkbox under another name   187      ;; :checkbutton is the same widget under GTK's name for it, which is
    ;; what libvidya calls it too — `"checkbutton" | "checkbox"` is one
    ;; arm of its tag table. frq writes both.
Read :active, and keep a field's text inside the field   190      ;; :active is what frq and libvidya call it — `props.bool("active")`
    ;; in libvidya's tag table — and :checked is what this backend called
    ;; it first. Both are read, because a client written against either
    ;; should not render a permanently empty tick; :active wins where
    ;; both appear.
    ;; Likewise both events fire. libvidya emits "toggled"; :on-change is
    ;; what the checkbox here answered to before.
    (:checkbox :checkbutton)
    (let [was (boolean (if (contains? props :active)
                         (:active props)
                         (:checked props)))
          id (c/next-id key)
          now (w/checkbox was s {:key key})]
      (record! n id)
      (when (not= now was)
        (fire! n :on-toggled now)
        (fire! n :on-change now)))
Write dvui's shape in jolt, on SDL3, with no shared object  Veronika Winters 208
    :slider (let [was (num (:value props) 0.0)
                  id (c/next-id key)
                  now (w/slider was {:key key
                                     :min (num (:min props) 0.0)
                                     :max (num (:max props) 100.0)})]
              ;; == and not not=, because a component holding a long 0 must
              ;; not be told every frame that its slider moved to 0.0
              (record! n id)
              (when-not (== now was) (fire! n :on-change now)))
    (:entry :text-entry)
    (let [was (str (or (:value props) (:text props) ""))
          id (c/next-id key)
          now (w/text-entry was {:key key :placeholder (:placeholder props)})]
      (record! n id)
      (when (not= now was) (fire! n :on-change now)))
    :progress (w/progress (num (:value props) 0.0))
    :separator (w/separator)
    (:spacer :gap) (w/spacer {:size (num (:size props) 8.0)
                              :expand (:expand props :none)})
    ;; An unknown tag is a container rather than an error, so a tree written
    ;; against a richer backend still shows its contents here — the same
    ;; bargain jolt-zvui makes with the tags it does not know.
    (c/box* (box-opts props key) (emit-children! n)))))
236;; --- the loop ----------------------------------------------------------------
238(defonce ^:private pending (atom []))
240(defn- schedule! [work] (swap! pending conj work) nil)
Give jvui a picture from somewhere else, and a clock   242;; --- timers -----------------------------------------------------------------
243;; A client needs somewhere to run work that is not a reaction to anything:
244;; frq drives its whole media plane from `(every! 16 pump!)`, and a decoded
245;; frame arrives because a timer asked for it rather than because a person
246;; clicked. There is no other hook of the right shape — a component body runs
247;; when its state changes, which for a video feed is never.
249;; Run from the same `:before` as the reconciler's queue, and for the same
250;; reason: a callback that patches the tree must not do it mid-walk.
252(defonce ^:private timers (atom {}))
253(defonce ^:private next-timer (atom 0))
255(defn- now-ms [] (System/currentTimeMillis))
257(defn after!
"Run `f` once, at least `ms` from now. Answers a handle for `cancel!`."
259
(let [id (swap! next-timer inc)]
  (swap! timers assoc id {:at (+ (now-ms) ms) :every nil :f f})
262
264(defn every!
"Run `f` every `ms`. Answers a handle for `cancel!`.
Every `ms` AT MOST, not exactly: it fires on the first frame after the
deadline, so a 16ms timer on a 60Hz window runs once a frame and on a
slower one runs less often. That is the right failure — a timer that tried
to catch up would run twice in a row on a stutter, and for a pump that
means two frames decoded and one shown."
272
(let [id (swap! next-timer inc)]
  (swap! timers assoc id {:at (+ (now-ms) ms) :every ms :f f})
275
277(defn cancel!
"Stop a timer."
(swap! timers dissoc id)
283(defn- run-timers! []
(let [t (now-ms)
      due (filter (fn [[_ v]] (<= (:at v) t)) @timers)]
  (doseq [[id {:keys [every f]}] due]
    (if every
      (swap! timers assoc-in [id :at] (+ t every))
      (swap! timers dissoc id))
    ;; A throwing timer is cancelled rather than allowed to throw every
    ;; frame for the rest of the session, which is unreadable and stops
    ;; the ones behind it.
    (try (f)
         (catch Exception e
           (swap! timers dissoc id)
           (println "glimmer-jvui: timer failed, cancelled:" (ex-message e)))))))
Write dvui's shape in jolt, on SDL3, with no shared object  Veronika Winters 298(defn- drain-pending! []
Give jvui a picture from somewhere else, and a clock   299  (run-timers!)
Write dvui's shape in jolt, on SDL3, with no shared object  Veronika Winters 300  (let [[ws] (reset-vals! pending [])]
  (doseq [w ws] (w))))
303(defn- run!
"glimmer.backend's :run. Creates the root page, mounts into it, then hands the
 loop to jvui.
 The reconciler's queued work is drained by jvui's `:before` hook rather than
 inside the walk: a re-render patches the tree, and patching a tree while it
 is being walked is how a frame ends up half old and half new."
[opts mount-root!]
(let [{:keys [title width height max-width theme frames auto-quit-ms shot]
       :or {title "glimmer" width 720 height 520}} opts
      root (create! :page (cond-> {} max-width (assoc :max-width max-width)))]
  (mount-root! root :page)
  (reset! b/loop-running? true)
316
    (app/run! (fn [] (emit! root))
              {:title title :width width :height height
               :theme (or theme theme/dark)
               :before drain-pending!
               :frames frames :auto-quit-ms auto-quit-ms :shot shot})
    (finally (reset! b/loop-running? false)))))
324;; --- registration ------------------------------------------------------------
326(def backend
{:name :jvui
 :create! create!               :apply-props!   apply-props!
 :append-child! append-child!   :remove-child!  remove-child!
 :replace-child! replace-child! :reorder-child! reorder-child!
 :schedule schedule!            :run            run!})
333(b/register! backend)
335;; --- headless driving, for tests ---------------------------------------------
337(defn root-node
"A bare root page, for mounting into without a window."
[] (create! :page {}))
341(defn render-once
"Walk `root` through jvui with no window, no font and no display.
 `cx` is a `jvui.core/context`; `evs` the events that frame. Answers the
 context, whose `:data` is every rectangle the walk placed — which is enough
 for a test to assert about a layout and to click on it."
([root cx] (render-once root cx []))
([root cx evs]
 (drain-pending!)
 (swap! cx assoc :events evs)
 (swap! cx c/apply-input evs)
 (binding [*record-rects?* true]
   (c/frame! cx (fn [] (emit! root))))
Give jvui a picture from somewhere else, and a clock   355
356;; --- feeds ------------------------------------------------------------------
357;; The same three calls glimmer-vidya exposes, so a client that paints a call
358;; does not care which backend is under it. They are not part of the
359;; reconciler and deliberately so: pixels arrive between frames, and the tree
360;; only ever holds the key.
362(defn frame-rgba!
"Hand feed `key` a new picture: `w` by `h` RGBA at FOREIGN pointer `px`.
The pointer is read during this call and not kept, so a caller may reuse
or free it immediately afterwards — which is what a decoder handing out a
borrowed buffer needs."
[key w h px]
(frames/put! key w h px))
371(defn frame-drop!
"Forget a feed and release its texture — someone left, or turned a camera
(frames/drop! key))
377(defn feed-keys
"Every feed with a picture."
(frames/keys*))
Answer the rest of what a client asks its window   381
382;; --- the platform -----------------------------------------------------------
383;; The rest of what glimmer-vidya answers, so a client can ask its backend
384;; about the window it is in without knowing which backend that is. Thin on
385;; purpose: every one of these is jvui.host, and the indirection exists so
386;; the client requires one namespace rather than two.
388(def set-title!          host/set-title!)
389(def window-width        host/window-width)
390(def screen-size         host/screen-size)
391(def quit!               host/quit!)
392(def open-url!           host/open-url!)
393(def clipboard-image-png! host/clipboard-image-png!)
395;; False and nil on a desktop, which is the right answer rather than a gap:
396;; the chooser exists so a phone can hand back a grant for one picture, and
397;; a caller reads the false and offers a file browser instead. glimmer-vidya
398;; says the same thing here.
399(def pick-image!         host/pick-image!)
400(def picked-image!       host/picked-image!)

Write dvui's shape in jolt, on SDL3, with no shared object 109c7e4 Veronika Winters 9d ago	1	(ns glimmer-jvui.core
	2	"A glimmer backend that renders through [jvui](../../../jvui).
	3
	4	glimmer owns the reactive core — ratoms, components, the reconciler — and
	5	knows nothing about any toolkit. glimmer-gtk fills that in with GtkWidgets,
	6	glimmer-vidya with a Rust node arena painted by egui, glimmer-gfx with a
	7	software rasterizer it writes itself. This fills it in with jvui, and so is
	8	the smallest of the four: everything a backend usually has to supply — the
	9	measuring, the placing, the hit testing, the painting — is already a toolkit
	10	one directory over.
	11
	12	What is left is the half an immediate-mode library does not have: a tree to
	13	hold still between frames. The reconciler needs somewhere to put a widget it
	14	created and to append a child to, and jvui's widgets draw and return within
	15	one call. So a node here is an atom of {:tag :props :children :key}, about
	16	thirty lines of it, and once a frame `emit!` walks that tree and calls the
	17	jvui widget each node names.
	18
	19	# The walk is the closure
	20
	21	glimmer-vidya's README explains why its tree lives in Rust: `ScrollArea` and
	22	`Frame` take an `FnOnce(&mut Ui)` and keep their begin/end private, so a
	23	push/pop ABI cannot scroll a page. jvui's containers take a body function
	24	for the same reason, and here the recursion is that function — `emit!` on
	25	a container passes `emit-children!` as the body, and the nesting takes care
	26	of itself.
	27
	28	# Why every node carries a key
	29
	30	jvui identifies a widget by its parent and its index among its siblings,
	31	unless it is given a `:key`, which replaces the index. A reconciler reorders
	32	children; an identity built on the index would hand each widget after the
	33	moved one the caret, the scroll offset and the drag of whichever widget used
	34	to sit at its index. So every node gets a serial number at creation and
	35	passes it as its key, and the identity follows the node rather than its
	36	position. That is the bug class zvui's README describes from the backend
	37	side, closed here at the other end."
	38	(:require [glimmer.backend :as b]
	39	[jvui.app :as app]
	40	[jvui.core :as c]
	41	[jvui.theme :as theme]
Give jvui a picture from somewhere else, and a clock 32fae8d nandi 9d ago	42	[jvui.widgets :as w]
Answer the rest of what a client asks its window 0b92f67 nandi 9d ago	43	[jvui.frames :as frames]
	44	[jvui.host :as host]))
Write dvui's shape in jolt, on SDL3, with no shared object 109c7e4 Veronika Winters 9d ago	45
	46	;; --- the retained tree -------------------------------------------------------
	47
	48	(defonce ^:private serial (atom 0))
	49
	50	(defn- create! [tag props]
	51	(atom {:tag tag :props props :children [] :key (swap! serial inc)}))
	52
	53	(defn- apply-props! [_tag n props] (swap! n assoc :props props) nil)
	54	(defn- append-child! [_t parent child] (swap! parent update :children conj child) nil)
	55	(defn- remove-child! [_t parent child]
	56	(swap! parent update :children #(vec (remove #{child} %))) nil)
	57	(defn- replace-child! [_t parent old new]
	58	(swap! parent update :children #(mapv (fn [c] (if (= c old) new c)) %)) nil)
	59	(defn- reorder-child! [_t parent child sibling]
	60	(swap! parent update :children
	61	(fn [cs]
	62	(let [cs (vec (remove #{child} cs))
	63	i (if (nil? sibling) 0 (inc (.indexOf cs sibling)))]
	64	(vec (concat (subvec cs 0 i) [child] (subvec cs i))))))
	65	nil)
	66
	67	;; --- props -------------------------------------------------------------------
	68
	69	(defn- txt [props] (str (or (:label props) (:text props) "")))
	70
	71	(defn- num [v default] (if (number? v) (double v) default))
	72
	73	(defn- box-opts
	74	"The container options shared by every container tag."
	75	[props key]
	76	(cond-> {:key key
	77	:dir (if (= :horizontal (:orientation props)) :horizontal :vertical)}
	78	(:spacing props) (assoc :spacing (num (:spacing props) 0.0))
	79	(:padding props) (assoc :padding (num (:padding props) 0.0))
	80	(:margin props) (assoc :margin (num (:margin props) 0.0))
	81	(:expand props) (assoc :expand (:expand props))))
	82
	83	(defn- fire! [n k & args]
	84	(when-let [f (get (:props @n) k)] (apply f args)))
	85
	86	;; --- the walk ----------------------------------------------------------------
	87
	88	(def ^:dynamic record-rects?
	89	"When true, each node keeps the rectangle jvui gave it, under `:rect`.
	90
	91	Off in a running window, where it would be a `swap!` per node per frame for
	92	nobody's benefit. On under `render-once`, so a test can click the centre of
	93	a button the way a person would, rather than guessing at a coordinate and
	94	re-guessing every time a padding changes."
	95	false)
	96
	97	(declare emit!)
	98
	99	(defn- record! [n id]
	100	(when record-rects? (swap! n assoc :rect (c/rect-of id)))
	101	nil)
	102
	103	(defn- emit-children! [n]
	104	(fn [_id _rect] (doseq [c (:children @n)] (emit! c))))
	105
	106	(defn- emit!
	107	"Render one node, and through it everything below it.
	108
109	A widget answers what the person did to it, and that answer is turned back
110	into the callback prop the component registered — which is the whole seam
111	between an immediate-mode toolkit and a retained, callback-shaped one."
112	[n]
113	(let [{:keys [tag props key]} @n
114	s (txt props)]
115	(case tag
116	:page (w/page* (cond-> {:key key}
117	(:max-width props) (assoc :max-width (:max-width props)))
118	(emit-children! n))
119
120	(:card :frame) (w/card* (box-opts props key) (emit-children! n))
121
122	:scroll (w/scroll* (assoc (box-opts props key)
123	:height (num (:height props) 200.0))
124	(emit-children! n))
125
126	:hbox (c/box* (assoc (box-opts props key) :dir :horizontal)
127	(emit-children! n))
128
129	(:vbox :box) (c/box* (box-opts props key) (emit-children! n))
130
Take the eight tags a client still had nowhere to put d5dfd53 nandi 9d ago	131	;; ONE tag for both kinds of picture: `:feed` is live pixels pushed
	132	;; in under a name and re-uploaded as they arrive, `:src` is a file
	133	;; decoded once and kept by path. Everything downstream — the fit, the
	134	;; bounds, the click — is the same, which is why libvidya makes this a
	135	;; prop and not a second tag, and why frq writes [:image {:feed k}]
	136	;; for a call tile and [:image {:src p}] for an attachment.
	137	;;
	138	;; The pixels never go through the reconciler either way: a frame
	139	;; arrives when the network says so, and a props diff at thirty a
	140	;; second would be a re-render per frame per peer.
	141	:image (let [id (c/next-id key)
	142	rect (w/image {:feed (:feed props) :src (:src props)}
	143	{:fit (:fit props)
	144	:max-width (:max-width props)
	145	:max-height (:max-height props)
	146	:size (:size props)
	147	:expand (:expand props)})]
	148	(record! n id)
	149	(when (:clicked? (c/interact! id rect)) (fire! n :on-click)))
	150
	151	:title-2 (w/title-2 s)
	152
	153	:status (w/status s (boolean (:live props)))
	154
	155	:spinner (w/spinner s)
	156
	157	:link (let [id (c/next-id key)]
	158	(record! n id)
	159	(when (w/link s {:key key}) (fire! n :on-click)))
	160
	161	:emoji (w/emoji (or (:emoji props) s) (:size props))
	162
	163	:avatar (w/avatar (or (:label props) s)
	164	(cond-> {}
	165	(:src props) (assoc :src (:src props))
	166	(:size props) (assoc :size (:size props))))
	167
	168	:reaction (let [id (c/next-id key)
	169	glyph (or (:emoji props) s)]
	170	(record! n id)
	171	(when (w/reaction glyph {:count (or (:count props) 0)
	172	:mine? (boolean (:mine props))
	173	:size (:size props)
	174	:key key})
	175	(fire! n :on-click)))
Give jvui a picture from somewhere else, and a clock 32fae8d nandi 9d ago	176
Write dvui's shape in jolt, on SDL3, with no shared object 109c7e4 Veronika Winters 9d ago	177	:title (w/title s)
	178
	179	:label (if (:dim props) (w/dim-label s) (w/label s))
	180	:dim-label (w/dim-label s)
	181
	182	:button (let [id (c/next-id key)
	183	hit? (w/button s {:key key :kind (or (:kind props) :normal)})]
	184	(record! n id)
	185	(when hit? (fire! n :on-click)))
	186
Take :checkbutton, which is :checkbox under another name 26defff nandi 9d ago	187	;; :checkbutton is the same widget under GTK's name for it, which is
	188	;; what libvidya calls it too — `"checkbutton" \| "checkbox"` is one
	189	;; arm of its tag table. frq writes both.
Read :active, and keep a field's text inside the field c131fc6 nandi 9d ago	190	;; :active is what frq and libvidya call it — `props.bool("active")`
	191	;; in libvidya's tag table — and :checked is what this backend called
	192	;; it first. Both are read, because a client written against either
	193	;; should not render a permanently empty tick; :active wins where
	194	;; both appear.
	195	;;
	196	;; Likewise both events fire. libvidya emits "toggled"; :on-change is
	197	;; what the checkbox here answered to before.
	198	(:checkbox :checkbutton)
	199	(let [was (boolean (if (contains? props :active)
	200	(:active props)
	201	(:checked props)))
	202	id (c/next-id key)
	203	now (w/checkbox was s {:key key})]
	204	(record! n id)
	205	(when (not= now was)
	206	(fire! n :on-toggled now)
	207	(fire! n :on-change now)))
Write dvui's shape in jolt, on SDL3, with no shared object 109c7e4 Veronika Winters 9d ago	208
	209	:slider (let [was (num (:value props) 0.0)
	210	id (c/next-id key)
	211	now (w/slider was {:key key
	212	:min (num (:min props) 0.0)
	213	:max (num (:max props) 100.0)})]
	214	;; == and not not=, because a component holding a long 0 must
	215	;; not be told every frame that its slider moved to 0.0
	216	(record! n id)
	217	(when-not (== now was) (fire! n :on-change now)))
	218
	219	(:entry :text-entry)
	220	(let [was (str (or (:value props) (:text props) ""))
	221	id (c/next-id key)
	222	now (w/text-entry was {:key key :placeholder (:placeholder props)})]
	223	(record! n id)
	224	(when (not= now was) (fire! n :on-change now)))
	225
	226	:progress (w/progress (num (:value props) 0.0))
	227	:separator (w/separator)
	228	(:spacer :gap) (w/spacer {:size (num (:size props) 8.0)
	229	:expand (:expand props :none)})
	230
	231	;; An unknown tag is a container rather than an error, so a tree written
	232	;; against a richer backend still shows its contents here — the same
	233	;; bargain jolt-zvui makes with the tags it does not know.
	234	(c/box* (box-opts props key) (emit-children! n)))))
	235
	236	;; --- the loop ----------------------------------------------------------------
	237
	238	(defonce ^:private pending (atom []))
	239
	240	(defn- schedule! [work] (swap! pending conj work) nil)
	241
Give jvui a picture from somewhere else, and a clock 32fae8d nandi 9d ago	242	;; --- timers -----------------------------------------------------------------
	243	;; A client needs somewhere to run work that is not a reaction to anything:
	244	;; frq drives its whole media plane from `(every! 16 pump!)`, and a decoded
	245	;; frame arrives because a timer asked for it rather than because a person
	246	;; clicked. There is no other hook of the right shape — a component body runs
	247	;; when its state changes, which for a video feed is never.
	248	;;
	249	;; Run from the same `:before` as the reconciler's queue, and for the same
	250	;; reason: a callback that patches the tree must not do it mid-walk.
	251
	252	(defonce ^:private timers (atom {}))
	253	(defonce ^:private next-timer (atom 0))
	254
	255	(defn- now-ms [] (System/currentTimeMillis))
	256
	257	(defn after!
	258	"Run `f` once, at least `ms` from now. Answers a handle for `cancel!`."
	259	[ms f]
	260	(let [id (swap! next-timer inc)]
	261	(swap! timers assoc id {:at (+ (now-ms) ms) :every nil :f f})
	262	id))
	263
	264	(defn every!
	265	"Run `f` every `ms`. Answers a handle for `cancel!`.
	266
	267	Every `ms` AT MOST, not exactly: it fires on the first frame after the
	268	deadline, so a 16ms timer on a 60Hz window runs once a frame and on a
	269	slower one runs less often. That is the right failure — a timer that tried
	270	to catch up would run twice in a row on a stutter, and for a pump that
	271	means two frames decoded and one shown."
	272	[ms f]
	273	(let [id (swap! next-timer inc)]
	274	(swap! timers assoc id {:at (+ (now-ms) ms) :every ms :f f})
	275	id))
	276
	277	(defn cancel!
	278	"Stop a timer."
	279	[id]
	280	(swap! timers dissoc id)
	281	nil)
	282
	283	(defn- run-timers! []
	284	(let [t (now-ms)
	285	due (filter (fn [[_ v]] (<= (:at v) t)) @timers)]
	286	(doseq [[id {:keys [every f]}] due]
	287	(if every
	288	(swap! timers assoc-in [id :at] (+ t every))
	289	(swap! timers dissoc id))
	290	;; A throwing timer is cancelled rather than allowed to throw every
	291	;; frame for the rest of the session, which is unreadable and stops
	292	;; the ones behind it.
	293	(try (f)
	294	(catch Exception e
	295	(swap! timers dissoc id)
	296	(println "glimmer-jvui: timer failed, cancelled:" (ex-message e)))))))
	297
Write dvui's shape in jolt, on SDL3, with no shared object 109c7e4 Veronika Winters 9d ago	298	(defn- drain-pending! []
Give jvui a picture from somewhere else, and a clock 32fae8d nandi 9d ago	299	(run-timers!)
Write dvui's shape in jolt, on SDL3, with no shared object 109c7e4 Veronika Winters 9d ago	300	(let [[ws] (reset-vals! pending [])]
	301	(doseq [w ws] (w))))
	302
	303	(defn- run!
	304	"glimmer.backend's :run. Creates the root page, mounts into it, then hands the
	305	loop to jvui.
	306
	307	The reconciler's queued work is drained by jvui's `:before` hook rather than
	308	inside the walk: a re-render patches the tree, and patching a tree while it
	309	is being walked is how a frame ends up half old and half new."
	310	[opts mount-root!]
	311	(let [{:keys [title width height max-width theme frames auto-quit-ms shot]
	312	:or {title "glimmer" width 720 height 520}} opts
	313	root (create! :page (cond-> {} max-width (assoc :max-width max-width)))]
	314	(mount-root! root :page)
	315	(reset! b/loop-running? true)
	316	(try
	317	(app/run! (fn [] (emit! root))
	318	{:title title :width width :height height
	319	:theme (or theme theme/dark)
	320	:before drain-pending!
	321	:frames frames :auto-quit-ms auto-quit-ms :shot shot})
	322	(finally (reset! b/loop-running? false)))))
	323
	324	;; --- registration ------------------------------------------------------------
	325
	326	(def backend
	327	{:name :jvui
	328	:create! create! :apply-props! apply-props!
	329	:append-child! append-child! :remove-child! remove-child!
	330	:replace-child! replace-child! :reorder-child! reorder-child!
	331	:schedule schedule! :run run!})
	332
	333	(b/register! backend)
	334
	335	;; --- headless driving, for tests ---------------------------------------------
	336
	337	(defn root-node
	338	"A bare root page, for mounting into without a window."
	339	[] (create! :page {}))
	340
	341	(defn render-once
	342	"Walk `root` through jvui with no window, no font and no display.
	343
	344	`cx` is a `jvui.core/context`; `evs` the events that frame. Answers the
	345	context, whose `:data` is every rectangle the walk placed — which is enough
	346	for a test to assert about a layout and to click on it."
	347	([root cx] (render-once root cx []))
	348	([root cx evs]
	349	(drain-pending!)
	350	(swap! cx assoc :events evs)
	351	(swap! cx c/apply-input evs)
	352	(binding [record-rects? true]
	353	(c/frame! cx (fn [] (emit! root))))
	354	cx))
Give jvui a picture from somewhere else, and a clock 32fae8d nandi 9d ago	355
	356	;; --- feeds ------------------------------------------------------------------
	357	;; The same three calls glimmer-vidya exposes, so a client that paints a call
	358	;; does not care which backend is under it. They are not part of the
	359	;; reconciler and deliberately so: pixels arrive between frames, and the tree
	360	;; only ever holds the key.
	361
	362	(defn frame-rgba!
	363	"Hand feed `key` a new picture: `w` by `h` RGBA at FOREIGN pointer `px`.
	364
	365	The pointer is read during this call and not kept, so a caller may reuse
	366	or free it immediately afterwards — which is what a decoder handing out a
	367	borrowed buffer needs."
	368	[key w h px]
	369	(frames/put! key w h px))
	370
	371	(defn frame-drop!
	372	"Forget a feed and release its texture — someone left, or turned a camera
	373	off."
	374	[key]
	375	(frames/drop! key))
	376
	377	(defn feed-keys
	378	"Every feed with a picture."
	379	[]
	380	(frames/keys*))
Answer the rest of what a client asks its window 0b92f67 nandi 9d ago	381
	382	;; --- the platform -----------------------------------------------------------
	383	;; The rest of what glimmer-vidya answers, so a client can ask its backend
	384	;; about the window it is in without knowing which backend that is. Thin on
	385	;; purpose: every one of these is jvui.host, and the indirection exists so
	386	;; the client requires one namespace rather than two.
	387
	388	(def set-title! host/set-title!)
	389	(def window-width host/window-width)
	390	(def screen-size host/screen-size)
	391	(def quit! host/quit!)
	392	(def open-url! host/open-url!)
	393	(def clipboard-image-png! host/clipboard-image-png!)
	394
	395	;; False and nil on a desktop, which is the right answer rather than a gap:
	396	;; the chooser exists so a phone can hand back a grant for one picture, and
	397	;; a caller reads the false and offers a file browser instead. glimmer-vidya
	398	;; says the same thing here.
	399	(def pick-image! host/pick-image!)
	400	(def picked-image! host/picked-image!)